Diamond Light Source Ltd, Harwell Science and Innovation Campus, Didcot, OX11 0DE, UK.
Research Complex at Harwell, Rutherford Appleton Laboratory, Harwell, Oxfordshire, OX11 0FA, UK.
Sci Rep. 2019 Jun 20;9(1):8913. doi: 10.1038/s41598-019-45561-w.
High energy X-ray phase contrast tomography is tremendously beneficial to the study of thick and dense materials with poor attenuation contrast. Recently, the X-ray speckle-based imaging technique has attracted widespread interest because multimodal contrast images can now be retrieved simultaneously using an inexpensive wavefront modulator and a less stringent experimental setup. However, it is time-consuming to perform high resolution phase tomography with the conventional step-scan mode because the accumulated time overhead severely limits the speed of data acquisition for each projection. Although phase information can be extracted from a single speckle image, the spatial resolution is deteriorated due to the use of a large correlation window to track the speckle displacement. Here we report a fast data acquisition strategy utilising a fly-scan mode for near field X-ray speckle-based phase tomography. Compared to the existing step-scan scheme, the data acquisition time can be significantly reduced by more than one order of magnitude without compromising spatial resolution. Furthermore, we have extended the proposed speckle-based fly-scan phase tomography into the previously challenging high X-ray energy region (120 keV). This development opens up opportunities for a wide range of applications where exposure time and radiation dose are critical.
高能 X 射线相衬层析成像技术对于研究具有较差衰减对比度的厚而密的材料具有巨大的益处。最近，基于 X 射线散斑的成像技术引起了广泛的关注，因为现在可以使用廉价的波前调制器和不那么严格的实验装置同时获取多模态对比度图像。然而，由于累积的时间开销严重限制了每个投影的采集速度，使用传统的步进扫描模式进行高分辨率相层析成像非常耗时。尽管可以从单个散斑图像中提取相位信息，但由于使用大相关窗口来跟踪散斑位移，空间分辨率会降低。在这里，我们报告了一种利用近场 X 射线散斑相层析成像的快速数据采集策略，采用飞扫模式。与现有的步进扫描方案相比，数据采集时间可以显著减少一个数量级以上，而不会影响空间分辨率。此外，我们已经将所提出的基于散斑的飞扫相层析成像扩展到以前具有挑战性的高 X 射线能量区域（120keV）。这一发展为那些对曝光时间和辐射剂量至关重要的广泛应用提供了机会。
